The thiazolidinedione, oxazolidinedione and hydantoin derivative compounds of formula (I) are known as “synthesis intermediaries” for preparing active pharmaceutical principles or as active pharmaceutical agents such as, for example, pioglitazone, rosiglitazone, troglitazone and ciglitazone.
Known in the prior art are methods for preparing thiazolidinedione, oxazolidinedione, and hydantoin derivative compounds:                via reduction in the presence of a metal hydride as described in WO 98/37073, or        via reduction in the presence of a transition metal as described in EP 257781, or        via reduction in the presence of magnesium and methanol as described in WO 98/37073.        
These various methods have the disadvantages of generating large amounts of impurities, which can exceed 10% in the synthesis of pioglitazone, of using a large amount of catalyst or solvent, and of having a selectivity problem in the isolation of the resultant compound of formula (I).